addPreRenderFunction calls requestRenderFrame

So there's no need to call requestRenderFrame prior to calling addPreRenderFunction.
Remove extra /**
Touch pan interaction request render frames
Touch rotate interaction requests render frames
Touch zoom interaction requests render frames
Merge pull request #528 from elemoine/touch

Touch interactions should use requestRenderFrame
decimal touch zoom
Merge branch 'master' of https://github.com/openlayers/ol3 into android_touch